With the increasing demand for the controllability and flexibility of primary equipment in power system and the fast development of power electronic technology

more and more power electronic equipment is applied. In this paper

power electronic primary equipment in power system is collectively called flexible primary equipment. From this point of view

this paper firstly reviews the research progress and engineering applications of flexible primary equipment and their key technologies in flexible AC transmission system

flexible DC transmission system

renewable energy power generation

power energy storage

active distribution system and microgrid. Then the key generic technologies of flexible primary equipment are analyzed

and its development trend is prospected.